AIMS: The aim of the current project was to determine if lycopene could modulate T-cell function and activity. METHODS: 1) Peripheral blood mononuclear cells (PBMC) were isolated from healthy adults and incubated with lycopene-enriched liposomes (0.0-1.2 μg/ml) then activated with or without the mitogens Con A, anti-CD3 and LPS and cultured for various lengths of time before measuring CD3, CD4, CD8, CD69, CD11a and CD25 expression.  the production of IL-1β, IL-2, IL-4, IL-6, IL-10, IL-17, IFN-γ, TGF-β and TNF-α were also measured along with the percentage of FoxP3 and IL-10 positive T-regulatory cells.  2) <i>Ex-vivo</i> expression of CD11a, CD49d, CD54, CD3 and CD69, as well as Con A stimulated proliferation were measured in subjects before and after a 12 week tomato-food and lycopene intervention study. RESULTS: Lycopene reduced PBMC proliferation and CD69 expression irrespective of the type of T-cell considered.  Lycopene reduced IL-2, IL-10, IL-17 and IFN-γ but increased IL-1β and TNF-α production.  lycopene also reduced the number of CD4⁺/CD25⁺ cells present as well as those positive for IL-10. Other parameters were not affected. CONCLUSION: Lycopene reduces T-cell activity by mechanisms dependent on early cell activation but this modulation is not specific to T-cell types.  the data support a potential beneficial effect of lycopene in the reduction of atherosclerosis through the modulation of T-cell function.